With the increasing depletion of fossil fuels and increasing pressure on environmental pollution, automotive industry urgently needs a new type energy resource to provide driving force for automobiles, and lithium-ion battery is talent showing itself due to its high energy density, no memory effect and high operating voltage, which makes the lithium-ion battery become a first choice for a power supply of the new energy vehicles at present. However, with expansion of the market demand for electronic products and development of power device and energy storage device, people's demand for the lithium-ion battery is continuously increasing, developing high energy density and fast charge-discharge lithium-ion battery becomes an urgent matter. At present, an effective method is to increase voltage and press density of an electrode active material and select appropriate electrolyte.
When the energy density of the lithium-ion battery is increased in order to meet requirements of use (such as improve the voltage of the lithium-ion battery), it is equivalent to increase an uncertainty of safety performance of the lithium-ion battery. For example, when lithium-ion battery is used under high temperature, oxidation and reduction reactions of the electrolyte will occurred acutely on the positive electrode film and negative electrode film and a large amount of gas will be generated, which will cause expansion of the lithium-ion battery. This will not only lead to damage of the lithium-ion battery, but also lead to damage of a device using the lithium-ion battery, even seriously, due to the expansion and deformation of the lithium-ion battery, a short circuit inside the lithium-ion battery will occur, or the electrolyte which is flammable will be leaked due to the swelling and bursting of the lithium-ion battery case, which will lead to a risk of fire and other safety accidents. Therefore, an effective technology is required to solve the problem of decomposition of the electrolyte and the problem of swelling of the lithium-ion battery.